Feeding mechanism for sewing machines



Oct. 22, 1935. N. v. CHRISTENSEN 2,018,439

FEEDING MECHANISM FOR SEWING MACHINES Filed July 8, 1932 5 Sheets-Sheet l Oct. 22, 1935.' Y N, v. CHRIS'II'ENSEN 2,018,439

FEEDING MECHANISM FOR SEWING MACHINES Filed July 8, 1952 3 Sheets-Sheet 2 iii Oct. 22, 1935.

N. v CHRISTENSEN FEEDING MECHANISM FOR SEWING MACHINES Filed JulyB, 1932 5 Sheets-Sheet 3 Patented Oct. 22, 1935 UNITED STATES PATENT OFFICE FEEDING MECHANISM FOR SEWING MACHINES Application July 8, 1932, Serial No. 621,460

3 Claims.

The invention relates to new and useful improvements in a feeding mechanism for sewing machines, and more particularly to a feeding mechanism for a sewing machine of the type shown in the patent granted Norman V. Christensen and Frederick F. Zeier, March 25, 1930, No.

1,751,508. In this patent, the main shaft is mounted above the Work support and extends in the general direction of the line of feed. The

feeding mechanism of the patent is of the fourmotion type. The feed bar receives all its movements from eccentrics on the main actuating shaft above the work support. The present invention has to do with an improvement in the 5 mechanism for operating the feed bar from this shaft above the work support.

An object of the present invention is to provide a mechanism for moving the feed bar back and forth, and for raising and lowering the feed bar,

which consists of few parts and direct connections, so that the feed bar may be moved at high speed with little or no lost motion.

A further object of the invention is to provide a feeding mechanism for a sewing machine of the above type wherein the feed bar is moved back and forth from an eccentric on the main shaft, and is raised and lowered by another eccentric on the main shaft, and wherein the only duty imposed upon the eccentrics is the operation of the 3 feed bar.

In the drawings Figure 1 is a side view of the machine with the improvements embodied therein,

Fig. 2 is a sectional view beneath the work support on the line 2-2 of Fig. 1, and showing" in a broken line the location of the axis of the main actuating shaft, and

Fig. 3 is a view partly in section and partly in plan showing the work support, the fabric guide and the feed dog.

The sewing machine to which the invention is applied consists of a supporting bed I having the usual supporting brackets on which the work support 2 is mounted. Mounted on the supporting bed and located at one side of the work support is a standard 3 which extends well above the Work support and is provided with suitable bearings for the main actuating shaft which is in. dicated at 4. Said shaft is driven by a belt wheel 5. The needle head 6 is carried by this standard andthe needle bar 1 reciprocates in the needle head and carries a needle 8. The needle bar is reciprocated by a crank connection with the main actuating shaft 4. Cooperating with the needle beneath the work support is a looper 9. The looper 9 is oscillated into and out of the needle thread loop! by an eccentric I0 on the main actuating shaft which is connected to the looper through a suitable train of mechanism. The looper is .5 given its needle avoiding movement through an eccentric II on the main actuating shaft, and through a suitable connecting train of mechamsm.

The material is fed across the work support by lo a feed dog I2 which operates in the usual slot formed in the throat plate carried by the work support 2 (see Fig. 3). The needle passes through an opening 13 in the throat plate. The feed is in the direction of the arrow (Fig. 3), and it will is be noted that the main actuating shaft lies in a vertical plane cutting the line of feed at an acute angle. The plane of the main actuating shaft is indicated at a, a in Fig. 3, of the drawings.

The present invention has particularly to do 20 with the means for operating the feed dog l2. The feed dog is carried by a feed bar I4. The feed dog is of the usual type and is provided with a shank 15 which, as shown in the present embodiment of the invention, is in turn clamped to 5 a supporting arm [6 connected to the feed bar I4. The feed bar I4 is connected to a feed rocker l1. Said feed rocker is in turn mounted for oscillation on a bar 3 attached to bearings I9 and 2!! carried by the bed of the machine. There is a sleeve bushing 2| in which one end of the bar is mounted, and a sleeve bushing 22 in which the other end of the bar is mounted, and the feed rocker oscillates on this bar between these bushings, which prevents the feed rocker from endwise movement 35 thereon. The feed rocker at its upper end is provided with spaced collars 23, 23 and a pin 24 is fixed to said collars. The feed bar I4 has a sleeve at its rear end which encircles this pin. Integral with the feed rocker is an arm 25. A stud 26 is attached to this arm and is adapted to be adjusted in a slot in the arm. An eccentric strap 21 is attached to the ball end of the stud 26. This eccentric strap 21 cooperates with an eccentric 28 on the main actuating shaft 4. The 45 feed bar is moved back and forth by this eccentric strap 21. The connections between the eccentric and the feed rocker are direct, that is, the eccentric strap cooperating with the eccentric is directly connected to an arm integral with the 50 feed rocker. This reduces to a minimum the number of parts necessary for the reciprocation of the feed bar.

Mounted in the other end of the feed bar is a pin 29 which is secured to the feed bar by a set screw 30. This pin passes through the arm l6 and serves as one supporting connection for the arm IE to the feed bar. At the rear end of the arm [6 is a screw 3| which passes through the arm into the feed bar, and the opening 3Ia, in the arm is of suflicient size so as to permit the arm to be slightly shifted on the pin when the screw 3| is loosened, said opening 31a is indicated in broken lines in Fig. 1 of the drawings. The feed dog may be tilted for leveling the dog or for raising the front end above the rear end or for raising the rear end above the front end. This is to suit the position of the feed dog to the particular material being operated upon. Attached to the outer end'of this pin 29 is a ball stud, and the lower end of the. eccentric strap 32 engages said ball stud. This eccentric strap cooperates with an eccentric 33 on the main actuating shaft 4.

It will be noted that the eccentric strap is directly connected to a pin which in turn is rigidly carried by the free end of the feed bar, so that the feed bar is raised and lowered by a direct connection between the feed bar and the eccentric on the main actuating shaft. The main actuating shaft, as noted above, is arranged in a plane at an acute angle to the line of feed. The ball stud carried by the pin 29 is substantially directly beneath the shaft. Likewise, the ball stud carried by the arm 25 is substantially directly beneath the main shaft. Therefore, the thrusts of the eccentrics which impart movement to the feed bar are direct vertical thrusts. Not only are the connections very direct so that there is no lost motion, but the duty placed upon the eccentrics is only that of operating the feedbar. When the feed dog is raised into contact with the fabric, it lifts the fabric against the presser foot'3 i which is yieldingly depressed by a spring 35 operating on a plunger 38 contacting with the arm 3? carrying the presser foot. In order to feed the fabric a definite stitch length and control the fabric during stitching, it is essential that the presser foot shall exert considerable pressure on the fabric. The feed dog is, however, raised and lowered by this direct eccentric connection with no .lost motion and with little or no vibration to the parts, even though the machine may be operating at a very high speed.

From the above it will be noted that the means for operating the feed dog is positive and'consists of few parts and with practically no intermediate devices with connections which are likely to wear and'to produce lost motion. Therefore, the feed dog is operated positively in its movements, and in proper timing for the uniform shifting of the fabric between each penetration thereof by the needle.

The machine is particularly of the type wherein the fabric is stitched at the edge thereof, and

a guide plate 38 is provided which extends along the edge of the work support and lies betweenthe moving fabric andthe reciprocating eccentric strap 32. This plate also guides the fabric so that it is free from contact with the eccentric strap '21 and the eccentric straps cooperating with the eccentrics 1B and II which operate the loo er.

' Mounted on the arm H5 carrying thefeed'dog is'a bracket 39 carrying a needle guide for positioning the needle relative to the path of movement of the looper.

It is obvious that minor changes in the details of construction may be 'made without departing from the spirit of the invention as set forth in the appended claims.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent, is-- r 1. In asewing machine, the combination of a supporting bed, a work support mounted thereon, a standard carried by said bed and disposed at one side of said work support, a main shaft mounted on said standard above said work support and extending in a direction at an acute angle to the line of feed, a feeding mechanism including a feed bar mounted beneath the work support, a feed dog carried thereby, a feed rocker to which said feed bar is attached, an eccentric on said main shaft, an eccentric strap cooperating therewith, an arm projecting from the feed rocker to which said eccentric strap is connected for moving the feed dog back and forth, a second eccentric on said main shaft, an eccentric strap cooperating therewith, and a member rigidly connected to said feed bar adjacent the free end thereof to which said last-named eccentric strap is directly connected for raising and lowering the feed dog.

2. In a sewing machine, the combination of a supporting bed, a work support mounted thereon, a standard carried by said bed and disposed at one side of said Work support, a main shaft mounted on said standard above said work support and extending in a direction at an acute angle to the line of feed, a feeding, mechanism including a feed bar mounted beneath the work support, a feed dog carried thereby, a feed rocker to which said feed bar is attached, an eccentric on said main shaft, an eccentric strap cooperating therewith, an arm projecting from the feed rocker to which said eccentric strap is connected for moving the feed dog back and forth, a second eccentric on said main shaft, an eccentric strap cooperating therewith, a member rigidly connected to said feed bar adjacent the free end thereof to which said last-named eccentric strap is directly connected for raising and lowering the feed dog, and a fabric guiding plate carried by said work support and located between the moving fabric and the eccentric straps which operate the feed bar.

7 3. In a sewing machine, the combination of a supporting bed, a work support mounted thereon, a standard carried by said bed and disposed at one side of said work support, a main shaft mounted on said standard above said work support and'extending in a direction at an acute eccentric on said main shaft, and an eccentric strap cooperating therewith and directly connected to said pin on the'feedbar for raising and low ering the feed dog.

NORMAN v. CHRISTENSEN. 

